This invention relates to a spinning machine with spinning stations, which comprise one drafting unit respectively, with depositing sites for cans containing sliver, and with transport devices for the transporting of the slivers from the cans to the spinning stations.
A spinning machine of this type, which is constructed as a ring spinning machine, is the state of the art based on the British Patent Document GB-PS 10 15 780. The transport devices comprise two transport belts for each spinning station which form a transport belt pair which receives a sliver between one another and transports it. Directly in front of the drafting unit, one of these transport belts winds around a drivable delivery roller. The delivery roller may tap its drive by way of a frictional wheel selectively from the feeding bottom cylinder of the pertaining drafting unit or--for an accelerated first-time drawing-in of a sliver--from a driving roller which can be driven much faster.
An interruption of the sliver transport in the case of a yarn breakage or other disturbance is not provided. However, in the case of a yarn breakage, there is the risk that the sliver which continues to be fed to the drafting unit leads to a lap formation at the delivery bottom cylinder of the drafting unit. The delivery bottom cylinders of the drafting units may be bent by means of such laps.
In the older German Patent Application P 41 24 312.9, corresponding to pending U.S. application Ser. No. 07/914,414, titled "Spinning Machine", which is no prior publication, it was suggested to stop the transport belt in the case of a yarn breakage while the drafting unit continues to run. This has the result that the sliver will tear off at any point between the transport device and the drafting unit so that, after the yarn breakage is eliminated, only a short starting piece of sliver will be available which does not permit a fast start of the operation of the spinning station.
In a further German Patent Application P 41 27 490.3, corresponding to pending U.S. application Ser. No. 07/886,813, titled "Ring Spinning Machine", which is also no prior publication, it was suggested that a transport belt of the transport device at the same time wind around the feeding bottom roller of the drafting unit so that the feeding bottom roller is at the same time the delivery roller for the transport belt. This delivery roller has a sleeve which can be uncoupled from a drivable shaft and is assigned to only one spinning station. Therefore the feeding roller pair of the drafting unit can be stopped together with the transport belt in the case of a yarn breakage. Such a construction is suitable only for short transport belts which have no bends because otherwise the feeding bottom roller of the drafting unit would be stressed by excessive lateral forces.
It is an object of the invention to largely avoid, in the case of a spinning machine of the initially mentioned type, disturbances in the drafting unit caused by a yarn breakage and thus difficulties with respect to a new start of its operation.
This object is achieved according to preferred embodiments of the invention in that the transport devices as well as the drafting units comprise devices which are controlled by means of a yarn detector detecting a faulty spinning unit and which interrupt the transport of an individual sliver.
In the case of this development, not only is the transport of the sliver in the transport device as well as in the drafting unit stopped, but at the same time the sliver remains threaded in the drafting unit so that the start of the operation can be fast when the operation of the spinning unit is started again. A fully automatic operation is also made possible in this manner.
At least the feeding bottom roller is expediently stopped in the case of the drafting unit. As experience has shown, it will then be possible, particularly in the case of three-cylinder drafting units, to restart the operation of the spinning unit in such a manner that the sliver is automatically placed in the remaining roller pairs. However, as an alternative, it is contemplated to also stop additional roller pairs of the drafting unit in the case of a yarn breakage.
Advantageously, the transport device comprises at least one transport belt to which a delivery roller is assigned which can be stopped. In this case, the transport belt may be wound around the delivery roller and the delivery roller may be arranged directly in front of the drafting unit.
In an advantageous development of the invention, the feeding bottom roller and the delivery roller are constructed as sleeves which can be coupled to a drive shaft which extends through in the longitudinal direction of the machine. In this case, the machine-side drives of the feeding bottom roller and of the delivery roller can continue to run while the feeding bottom roller and the delivery roller itself can nevertheless be stopped.
Advantageously, the devices for interrupting the transport of the sliver are operated pneumatically according to certain preferred embodiments of the invention. Since nowadays spinning machines normally have pneumatic connections anyhow, a simple and economical operation is possible in this manner. In this case, during the normal spinning operation, the devices are expediently acted upon by excess pressure which can be reduced in the case of a disturbance. This has the result that, in the case of a disturbance, for example, in the case of a power failure, the excess pressure-will no longer exist so that in such a case the transport devices and the drafting units are necessarily stopped.
In a further development of the invention, the yarn detector is arranged on a carriage which can be moved along the spinning machine and is assigned to several spinning stations. This has the advantage that only one yarn detector, which periodically monitors the spinning stations, is required for a plurality of spinning stations. Experience has shown that such a periodic monitoring is possible in the case of certain spinning machines, particularly in the case of ring spinning machines.
Other objects, advantages and novel features of the present invention will become apparent from the following detailed description of the invention when considered in conjunction with the accompanying drawings.